| Principle of parsimony (Occam’s razor) |
An assertion that all else being equal, models with fewer redundant features are likely to be truer than rival models (Baker, 2022). This assertion reflects an objective preference for parsimony rather than a subjective preference for simplicity or elegance. In this way, and contrary to misconception, the principle of parsimony does not imply that reality, or its truest models, are simple or elegant. |
| Trueness (bias) |
Distance between expected and true estimates of model parameters (ISO, 1994). True values of model parameters are typically inaccessible, and trueness (bias) can therefore be defined only in relative terms. The principle of parsimony asserts that all else being equal, models with fewer redundant features have truer (less biased) parameter estimates relative to rival models. |
| Precision (variance) |
Expected distance between repeated estimates of model parameters (ISO, 1994). Precision (variance) does not require knowledge of the true values of model parameters and can therefore be defined in absolute terms. The problem of irreplicable results (Ioannidis, 2005) is primarily a problem of precision (variance). |
| Circular analysis |
An analysis that first tests a model in a way that almost invariably accepts the model and then accepts the model on the basis of this test. This definition includes circular analyses of knowledge that accept overspecified models or redundant (less true) explanations. It also includes circular analyses of noise that accept overfitted models or irreplicable (less precise) explanations (Kriegeskorte et al., 2009). |
| Neural circuits or brain networks |
Groups of connected neurons or brain regions that mediate function. This definition does not intend to make analogies between groups of neurons or brain regions, and electronic circuits or artificial neural networks (Rubinov, 2015). |
| Function |
Behavior and other action that helps animals to survive and reproduce (Roux, 2014). This definition excludes physiological phenomena that lack such useful action. |
| Structure |
Anatomical or physiological organization. This definition encompasses all physiological phenomena, including phenomena that lack known function. |
| Development |
Formation of structure before and after birth. This definition includes plasticity and therefore encompasses learning and memory. |
